From SE 464830, it is previously known, in a heavily loaded gear, such as a planetary gear in a vehicle gearbox, to distribute and guide lubricant by means of a specially designed ring in such a way that all the teeth on a gearwheel in the gear are lubricated at the same time. This is brought about by means of a circular-arc-shaped groove in the ring which bears against the end surface of the gearwheel, the groove being open toward the gearwheel. The groove extends around the entire periphery of the ring. Lubricant is fed to the groove from a pressurized duct. The groove is made concentrically with the gearwheel and has an outer delimiting surface which lies radially slightly outside the bottom surface in the tooth gaps between the teeth on the gearwheel. In this way, narrow apertures are formed in the tooth gaps between the teeth, where the groove is open in toward the tooth gaps (see in particular FIG. 2 in SE 464830). Accordingly, the gearwheel is mounted on its shaft by a spline joint.
SE 514231 discloses a range gearbox of planetary gear type in which a spline joint is located directly adjacent to the teeth of the sun wheel. Here, the teeth on the sun wheel are extended at one end. A coupling ring has internal teeth which fit in the gaps between the extended teeth on the sun wheel. In the assembled state, a spline joint is then formed by these internal teeth and extended teeth. The spline joint means that the coupling ring is connected to the sun wheel in a rotationally fixed manner. The lubrication of the sun wheel cannot take place in the same way as in SE 464830, as the coupling ring is in the way. As indicated in the figures of SE 464830, lubricating oil is instead conducted from a central hole in the main shaft via a radially drilled hole to an annular groove on the inside of the sun wheel. From the groove, the lubricating oil is then distributed through small radial holes which are drilled in the bottom of each gap between the teeth on the sun wheel. This solution provides excellent lubrication, but the many small holes are disadvantageous as far as production is concerned and lead to inferior strength of the teeth in the sun wheel.
Against the background of the above, the object of the invention is therefore to make it possible to lubricate extended gearwheels, where the extended part of the gearwheel constitutes splines in a spline joint for securing, for example, a coupling ring, without weakening the teeth on the sun wheel, and also to facilitate the manufacture of the lubricating device.